Justin Davis began training camp as the third tailback on USC's depth chart behind Javorius Allen and Tre Madden.
He might have a higher profile in the Aug. 30 opener against Fresno State.
Madden is nursing a toe injury that could make him questionable for the first game.
Madden, who did not practice Wednesday or Thursday, saw a foot specialist but USC was awaiting exam results, Coach Steve Sarkisian said after practice.
"We're taking every precautionary action we can to make sure that Tre is great and ready to go when his time is called again," Sarkisian said.
Madden began training camp fit and recovered from the hamstring injury that plagued him during the second half of the 2013 season.
He rushed for more than 100 yards in four of the first five games before he was injured against Arizona.
Madden's recent absence has created more opportunities for Davis. The sophomore appears fully recovered from the broken ankle he suffered last season against Notre Dame.
Davis performed well in two training camp scrimmages at the Coliseum and in practice this week.
If Madden is sidelined for the opener, the Trojans would rely on Allen and Davis and fullbacks Soma Vainuku and Jahleel Pinner.
"We're not in the worst-case scenario," Sarkisian said. "But I sure would like to have Tre out there with us. He's a really talented guy."
Dixon stepping up
With Jalen Cope-Fitzpatrick academically ineligible, freshman Bryce Dixon and fifth-year senior Randall Telfer are the Trojans' only scholarship tight ends.
So Dixon has leaned on Telfer for guidance.
"Randall's been always by my side pushing me," Dixon said. "Kind of like a big brother."
Senior walk-on Chris Willson also has eased Dixon's transition to college football.
Dixon, 6 feet 4 and 240 pounds, moved from wide receiver to tight end before his senior season at Ventura St. Bonaventure High.
He catches and runs extremely well. The blocking component is improving.
"Over the course of getting stronger and getting technique down, I should be a real good blocker," he said.
Kicking game improving
Kicker Andre Heidari struggled early in training camp and appeared to be facing a challenge from newcomer Matt Boermeester.
But Heidari, who made 15 of 22 field-goal attempts last season, "is kicking the ball really well for us right now," Sarkisian said.
This will be Heidari's fourth season as the starting kicker. He has made 40 of 55 field-goal attempts.
Punter Kris Albarado has consistently kicked well since training camp began.
"Kris continues to just boom the ball," Sarkisian said.
Last season, Albarado averaged 37.1 yards per punt in a special-teams scheme designed to prevent returns.
The new staff apparently will not restrict Albarado.
Mitchell overcoming additional surgeries
Receiver Steven Mitchell is attempting to overcome more than the major knee surgery that sidelined him last season.
Since spring, Mitchell has undergone two surgical procedures for a groin issue.
The first forced the redshirt freshman to sit out the final three weeks of spring practice. A second procedure was performed during the summer.
Mitchell has struggled to regain the burst that made him a top recruit from Mission Hills Alemany High.
Sarkisian has not spoken of the surgeries with reporters when discussing Mitchell's progress during training camp. But when asked Wednesday night by The Times, Sarkisian said the combination of injuries and surgical procedures had limited Mitchell.
"When you don't have the chance to run and you're rehabbing a knee, then you are rehabbing your groin and you're not really physically doing leg activities, your strength just isn't the same," Sarkisian said. "He'll get it back and he'll be fine."
Mitchell was not among players made available to the media Wednesday or Thursday.
Several veteran players were given days off from practice during training camp to allow them extra rest. On Thursday, freshman offensive lineman Toa Lobendahn was held out for the same reason, Sarkisian said. Lobendahn is on track to start at guard and he also has practiced as the backup center.
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